Their political fates now entwined, President Barack Obama is imploring voters to elect Hillary Clinton to the White House, appealing to the women, minorities and young people who powered his rise and are now crucial to hers.

Rep. Elijah Cummings, D-Maryland, gives two thumbs up following his speech during the first day of the Democratic National Convention in Philadelphia , Monday, July 25, 2016. (AP Photo/Paul Sancya)

Rep. Elijah Cummings, D-Maryland, gives two thumbs up following his speech during the first day of the Democratic National Convention in Philadelphia , Monday, July 25, 2016. (AP Photo/Paul Sancya)

Obama’s address on July 27 at the Democratic convention is a moment steeped in symbolism, the passing of the baton from a barrier-breaking president to a candidate trying to make history herself. Obama’s robust support for Clinton, his political foe-turned-friend, is also driven by deep concern that Republican Donald Trump might win in November and unravel the president’s eight years in office.

In excerpts released ahead of his speech, Obama acknowledged the economic and security anxieties that have helped fuel Trump’s rise, but he argued they don’t define the country.

“The America I know is full of courage and optimism and ingenuity,” Obama said.

Trump fueled more controversy Wednesday when he encouraged Russia to meddle in the presidential campaign — even as he dismissed suggestions from Obama and other Democrats that Moscow was already acting on his behalf.

On the heels of reports that Russia may have hacked Democratic Party emails, Trump said, “Russia, if you’re listening,” it would be desirable to see Moscow find the thousands of emails Clinton says she deleted during her years as secretary of state. At about the same time, Trump’s running mate, Mike Pence, declared there would be “serious consequences” if Russia interfered in U.S. politics.

To Obama and Clinton, Trump’s comments only fed their contention that the billionaire businessman is unqualified to be commander in chief. Trump has no national security experience and few ties to the norms that have governed U.S. foreign policy under presidents from both parties, including standing by NATO allies threatened by countries including Russia.

“This has to be the first time that a major presidential candidate has actively encouraged a foreign power to conduct espionage against his political opponent,” said Clinton adviser Jake Sullivan.

Wednesday night’s Democratic lineup was aimed at emphasizing Clinton’s own national security credentials, a shift from two nights focused more on re-introducing her to voters as a champion for women’s issues, children and families. Among those taking the stage is former Pentagon and CIA chief Leon Panetta, who served alongside Clinton in Obama’s Cabinet.

Obama, too, was vouching for Clinton’s national security experience, recalling their work together during trying times.

“Even in the middle of crisis, she listens to people, and keeps her cool, and treats everybody with respect,” he said in speech experts. “And no matter how daunting the odds, no matter how much people try to knock her down, she never, ever quits.”

Obama was closing a night also featuring Vice President Joe Biden, and Clinton’s running mate, Virginia Sen. Tim Kaine.

In a move aimed at broadening Clinton’s appeal, New York City Mayor Michael Bloomberg — an independent who considered launching a third party bid for president — will endorse the Democratic nominee.

Clinton’s campaign believes Trump’s unorthodox candidacy will turn off moderate Republicans, particularly women, who worry he’s too unpredictable to take the helm in a turbulent world. They recognize that Republicans, as well as many Democrats, have questions about Clinton’s character but hope to ease those concerns.

Still, the core of Clinton’s strategy is putting back together Obama’s winning White House coalition. In both his campaigns, Obama carried more than 90 percent of Black voters, the overwhelming majority of Hispanics, and more than half of young people and women.

That coalition was vividly on display in the first two nights of the convention in Philadelphia. Women lawmakers were prominently featured, along with young activists, immigrants, and mothers whose Black children were victims of gun violence or killed during encounters with law enforcement.

Gun violence continued as a theme Wednesday night as families of mass shooting victims took the stage. Delegates rose in an emotional standing ovation for the mother of one of the victims in last month’s Orlando nightclub shooting, who asked why “commonsense” gun policies weren’t in place when her son died.

“I never want you to ask that question about your child,” Christine Leinonen said.

Capping the somber section of the program focused on gun violence, a group of Broadway singers performed a rousing rendition of “What the World Needs Now Is Love,” as the audience sang and swayed in unison.

Clinton’s base-boosting strategy has some Democrats worried that she is ceding too much ground to her opponent. Her convention has made little mention of the economic insecurity and anxiety that has, in part, fueled Trump’s rise with White, working-class voters.

Trump has cast himself as the “law-and-order” candidate and has promised to get tough on terrorists. Democrats have little noted the threat of terrorism or the Islamic State group, though both were expected to get more attention Wednesday night.

Clinton’s convention has been awash in history, with energized delegates celebrating her formal nomination as the first woman to ever lead a major political party in the general election. Some supporters of Clinton’s primary rival, Bernie Sanders, continued to voice their displeasure with the pick, but there was nothing they could do to take the nomination away from Clinton.

“As of yesterday, I guess, officially our campaign ended,” Sanders acknowledged during a meeting with New England delegates.